Spawn of Kyuss

Whenever Spawn of Kyuss deals any damage to a creature, put a worm counter on that creature.
Whenever a creature with a worm counter on it dies, return that creature to the battlefield under your control. It gains, "Whenever this creature deals damage of any kind to another creature, put a worm counter on that other creature."
Of all Elder Evils, the Worm that Walks has the most original way of spreading influence.